Much information is known concerning the manner in which alcohols increase the fluidity of the hydrocarbon chains in biomembranes. The question whether this alteration changes the interfacial region between the membrane and its local aqueous environment has not, however, been addressed. Also unanswered is the question whether alcohols have a direct action at biological interfaces independent of the processes occuring within the bilayer. In the accepted description of synaptic transmission, there are a number of processes involving neurotransmitter transport across or interaction with membrane interfaces. No measurements of these phenomena exist; consequently the size and scope of alterations induced by alcohols at these interfacial regions are not known. This project will initiate a study which, in the long term, will respond to the question: are these interfacical barriers influenced by alcohol in vivo and, if so, does this modification contribute an as yet unconsidered component of their depressive action? In this investigation, a recently developed rotating diffusion cell (RDC) will be used to evaluate in vitro solute interfacial transfer kinetics across a model biological interface. Experiments will be performed in the presence and absence of various concentrations of first ethanol and then other alcohols dissolved in the aqueous phase. The RDC technique presents a simple, newly available and accurate means to quantify interfacial transport; the physiological data obtainable is novel and provides information concerning membrane interface events that have previously been ignored or considered too difficult to measure. The question "does alcohol modify interfacial transfer?" will be addressed using four model solutes and two neurotransmitters. A positive response will provide impetus to apply the information to transport experiments using both liposomes and synaptosomes, designed to approach more closely the in vivo situation.